Why should we write the clause "Jiang Taigong is here, the gods abdicate" when building a new house?

According to legend, in the early Western Zhou Dynasty, there was a Songjiazhuang in the east of Jiangyuan, Jiang Taigong's hometown. The owner of the village, Song Dynasty, was very rich. He and Jiang Taigong are good friends who burn incense and swear. One year, Song Yiren thought their house was dilapidated and wanted to build a new one. So, he found someone to choose a land of feng shui and chose a good day to go to work. However, it was not covered several times in a row. For the first time, the walls around the house were built. A strong wind blew it down, and the fourth girder was just finished for the second time. In an instant, all four beams of five rooms were broken. When it was built for the third time, the roof was covered with firewood and grass, and it was cleaned by fire. Helpless, Song Yiren simply left the principal room and hastily built a hatchback room for the night. Soon, he returned to his hometown from Qi to visit his mother. On this day, he was free to visit his good friend Yi Song. I haven't seen you for many years, and it's very close. The two of them never talk about the ups and downs after continuous separation. At this time, Jiang Taigong saw that the kitchen built in the Song Dynasty was still a broken wall and did not cover the main house? I was puzzled by this, so I asked Song Shi what was going on. With a sad face, Song told the unfortunate story of building a house. Jiang Taigong immediately understood. He smiled and said, "It turned out to be such a trivial matter. Dear friends, don't worry, the day after tomorrow will be auspicious, and the purple star will come. Start building a house. " Two days passed quickly, so it's time to beam. Jiang Taigong came to the new house, stood by the garden and murmured, "Four Ghosts, wash your ears. Listen, Taigong is here, and everyone belongs to him. " The next day, Song made a suspicious move, which was really effective. In a few words, Song built a safe house, and only a few days later, he successfully built a new house. What's going on here? It turned out that when people began to build new houses in the Song Dynasty, ghosts and gods from all directions came to fight for territory and received incense. You fight for me, make waves, tear down walls, kick off beams, and a jack-o'-lantern is missing a lamp. To this end, Song Yiren was daunting. When the house was built this time, ghosts and gods heard the letter again. Jiang Taigong suddenly appeared in front of them, shaking with fear. Because they were all blocked by Jiang Taigong, and more importantly, Jiang Taigong had a whip to whip the gods, fearing that he would be punished in his hands. So, Jiang Taigong said, as soon as the house stopped, they all ran away in fear.

Later, the story spread, and everyone who built a new house had to follow the example of the different people in the Song Dynasty. In order to get good luck, they wrote a couplet of "ecliptic on the beam and purple star on the column". Write the clause "Jiang Taigong abdicates here" on the flower garden, and some people tie a pair of chopsticks and a string of copper coins on the flower garden with a red rope, which means: food, clothing, housing and transportation, money. I want Jiang Taigong to stay for a long time, so that my family will be safe forever. This custom has been followed for more than 3000 years and is still used by most people when building houses.